Spring Boot+JPA+Mysql+ThymeLeaf快速構建CURD系統（三）構建後端

上一篇我們已經成功搭建了一個SpringBoot的工程，在這個基礎上實現一個通信錄功能的CURD的Demo程序，本篇講述如何構建後端部分。

由於重點是演示SpringBoot，我們就簡化這個通信錄，在Mysql中新建一個Person表，包含Id，Name和Phone三個字段，初始化SQL語句如下：

CREATE TABLE `Person` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(11) DEFAULT NULL,
  `phone` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

爲了在SpringBoot中連接Mysql數據庫，首先在pom文件中增加如下三個依賴：

        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

增加後進行Maven Update Project後在Maven Dependency中就可以看到新增的依賴包。

新建一個package，名字爲jpa，用來放數據庫相關的處理的類，新建一個類DataSourceConfig.java，代碼如下：

package com.springBoot.curdDemo.jpa;

import java.util.Properties;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@EnableTransactionManagement
public class DataSourceConfig {

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://***.***.***.***:3306/curdDemo?useUnicode=true&characterEncoding=UTF-8");// 填入你的mysql的訪問url
        dataSource.setUsername("***");// mysql用戶名
        dataSource.setPassword("***");// mysql訪問密碼
        return dataSource;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean entityManagerFactory = new LocalContainerEntityManagerFactoryBean();

        entityManagerFactory.setDataSource(dataSource);

        entityManagerFactory.setPackagesToScan("com.springBoot.curdDemo.jpa.entity");// mapping類的存放路徑

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        entityManagerFactory.setJpaVendorAdapter(vendorAdapter);

        Properties additionalProperties = new Properties();
        additionalProperties.put("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
        additionalProperties.put("hibernate.show_sql", "false");
        additionalProperties.put("hibernate.hbm2ddl.auto", "none");
        entityManagerFactory.setJpaProperties(additionalProperties);

        return entityManagerFactory;
    }

    @Bean
    public JpaTransactionManager transactionManager() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(
                entityManagerFactory.getObject());
        return transactionManager;
    }

    @Bean
    public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
        return new PersistenceExceptionTranslationPostProcessor();
    }

    @Autowired
    private DataSource dataSource;

    @Autowired
    private LocalContainerEntityManagerFactoryBean entityManagerFactory;
}

這個類用於配置和MySql的連接以及Hibernate的屬性，Spring 3以後的中心思想就是”約定大於配置”，這裏配置了DataSource, LocalContainerEntityManagerFactoryBean, JpaTransactionManager等Bean在Spring的上下文中，由於我們只配置了這些數據庫相關的Bean，Spring會自動使用這些Bean作爲JPA的底層配置。

我們配置了mapping類的存放路徑爲com.springBoot.curdDemo.jpa.entity，那麼下一步就新建這個package，然後建立一個類來mapping數據庫中的Person表。該類代碼如下：

package com.springBoot.curdDemo.jpa.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "Person")
public class Person {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Integer id;

    @Column(name = "name")
    private String name;

    @Column(name = "phone")
    private String phone;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

}

數據庫部分最後構建一個Respository接口，代碼如下：

package com.springBoot.curdDemo.jpa;

import org.springframework.data.repository.PagingAndSortingRepository;

import com.springBoot.curdDemo.jpa.entity.Person;

public interface PersonRespository extends PagingAndSortingRepository<Person, Integer> {

}

數據庫部分構建完畢後，構建Service層，本文的Service層就直接寫4個方法，對應CURD，源碼如下：

package com.springBoot.curdDemo.service;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.springBoot.curdDemo.jpa.PersonRespository;
import com.springBoot.curdDemo.jpa.entity.Person;

@Service
public class PersonService {

    @Autowired
    PersonRespository personRespository;

    public void create(String name, String phone) {
        Person person = new Person();
        person.setName(name);
        person.setPhone(phone);
        personRespository.save(person);
    }

    public void update(Integer id, String name, String phone) {
        Person person = personRespository.findOne(id);
        person.setName(name);
        person.setPhone(phone);
        personRespository.save(person);
    }

    public List<Person> read() {
        List<Person> persons = new ArrayList<Person>();
        Iterator<Person> it = personRespository.findAll().iterator();
        while (it.hasNext()) {
            Person person = it.next();
            persons.add(person);
        }
        return persons;
    }

    public void delete(Integer id) {
        personRespository.delete(id);
    }
}

至此，後端部分就構建完畢了，這是目錄結構如下：